GPS wiring

[Colin J Monteith]

I snipped off the proprietary BMW GPS plug under the handlebar so I can fit my own Garmin 390 to this power source. Just to be safe I confirmed polarity with my multimeter but did not look at the actual voltage before dropping the meter and it's broken now. I was going to do it again to get voltage but........ Question while I wait for new multimeter I just ordered to arrive by mail. Is the power at the supply side 12V at that stage still or because it's dedicated to the GPS has it been reduced already to the typical requirement of 5v?

 

[Colin J Monteith]

It is 12V just in case you plan to mount an accessory that is not tolerant to a wide voltage range. Most accessories will simply not charge or shut down if it's not right but better to be safe. Either use the supplied resistor built into the Garmin wiring or add one. Of course same principle apples to any accessory If not Garmin.